Process of making acoustical tile



Jan- 8, 1952 l G. s. wlLLr-:Y ErAL 2,581,993

PRCESS OF MAKING ACOUSTICAL TILE original Filed sept'. 17, 1943 ,Invenian; Gra-772251 MZIJZZ@ I Orca Patented Jan. 8, 1952 PROCESS OFMAKING ACOUSTICAL TILE Grant S. Willey, Chicago, Ill., and Orcutt W.Frost, Gaston, Oreg., assignors to United States Gypsum Company,Chicago, Ill., a corporation f Illinois Original application September17, 1943, Serial No. 502,728. lDivided and this application December 6,1948, Serial No. 63,718

2 Claims. 1

This invention pertains to an acoustical construction. More particularlyit is directed to a fibrous acoustical base having a decorative coatingreceptive surface and the process of making the same.

This is a division of the application for Letters Patent, Serial Number502,728, filed September 17, 1943, and issued as Patent Number 2,459,121on January ll, 1949.

Though the principles underlying this invention yare adapted to thepreferred type of an acoustical base comprising brillatedlignocellulosic materials felted in a sheet form in accordance withconventional' methods of formation, it is not the intention to limit thesame to the preferred embodiment, since obviously, with slightembodiment the depth to which the grooves are cut in the acoustical tilebody. y

Figure 3 is taken along lines 3--3 of Figure l, partly broken away toshow a section through one of the grooves and indicate but one type ofperiphery or are impressed within the acoustical base.

Figure 4 shows in a partly broken away section another type of arc of asemicircular nature, that may be also impressed depending on otherrelative conditions inherently present in the acoustical base.

Figure y5 illustrates ina transverse section another modication of thisinvention.

An acoustical base I0, preferably comprising felted lignocellulosefibrous materials, such as used in conventional insulation board istreated to the simultaneous application of heat and pressure to developin the surface thereof an autogenously formed thermoplastic resin thatnot only binds the fibrous material on the surface I2 to form a moredense and decorative medium receptive plane but also maintains thecontiguous area I2a at a greater density in comparison with interiorI2b. The development and formation of this autogenously createdthermoplastic lignocellulosic resin is highly desirable, since itprovides a smooth surface for the subsequent application of paint,lacquer and other decorative finishes without undue difficulty. Asurface of this nature though it is somewhat impervious to sound, it is,however, more protective, resistant to sculiing and denting, and moreeasily adapted to use under erection conditions.

To form this surface it is desirable that the lignocellulosic blanks beplaced in contact with a heated surface maintained under very slightpressure to prevent undue compression in the interior I2b of theacoustical base I 0. If great pressure is applied the interior I2b has atendency to densify as the heat from the surface penetrates the depth ofthe acoustical base Ill. In practice it was found desirable to use atemperature of about 485 F. to catalyse and aid in the formation of theautogenously created lignocellulosic resins on the surface I2, and thesurface contiguously underlying area I 2a. The length of heat andpressure application will vary withv the nature of the base. Though itis desirable to pre-dry the acoustical blanks, it is not essential sincethe open, cellular structure permits the ready escape of gases and watergenerated during the autogenous formation of the thermoplasticligno-cellulosic resin.

A series ISa, b, c, d, etc. of parallel slots or grooves I6 areimpressed upon and through the surface I2 into the interior I2b of theacoustical' base I0. In order to obtain the maximum benefit, it isdesirable to form the grooves I6 as deeply as possible to provide themaximum surfacearea capable of absorbing sound. In any event it isdesirable that the depth of the cut or groove I6 be at least one half ofthe thickness of the acoustical base I0.

In practice the parallel grooves are formed in the acoustical base I0,and extend approximately one third of the Way across the face I2 of theacoustical base I0. At this point 24, another series Ia, b, c, d, etc.set off or staggered in relationship to the previous series ISa, b, c,d,etc. is started across another approximate third of the way of theface to the point 26. The ends of theV series I8, a, b, c, d, etc. isslightly overlapped but not joined by endsof the series IGa, b, c, d,etc. at point 24, and by the ends of the series 20, a, b, c, d, etc. atpoint 26. This type of construction provides for more acoustical basematerial between the grooves I6 and I8 and prevents a transverse planeof cleavage or weakness along successive grooves at this junction.Obviously other patterns employing these principles can also be made.

To aid and reinforce this junction as well as for other reasons givenbelow, the end sides30 of the grooves IIS near the points 24 and 26, asWell as at Vthe edges of the acoustical base II), gradually slope 32 inaforrn of an arc to the bottom 23 of the groove. The substantiallyelliptical type arc of the groove (as shown in Figure 3) is obtained byimpressing the cutting means (not shown) into the interior |25 and thno'fig the cutting means longitudinally the desired distance. Thisparticular type of groove 'construction is particularly useful in'slottiii'g acoustical bases having a thickness of less than one inch.

Obviously another type is the circular arc yas shown in Figure 4. Ifrelatively small diarileter cutting saws are used, the proper depth canbe readily reached without cutting longitudinally.

To nish the tile a bevel I!! can be formed on all edges either duringthe pressing operations or at subsequent stages of operation before theapplication of coatingV compositions to the formed surface.

A 's1ot'22 is also'ferned in at least two of the sides of the acousticalbase Iii to provide a means for insertion of a bridge clip (not shovvn)or other suitable retaining means, to'at'tachV the tile rne-V chanicallyto the surface, such "as a Wall or a ceiling. in praetice, it'frequently isdesirable to use an adhesive vbacking on the tile, vWhichis then 'erected and retained in place by the adnsive. f

The slope v32 curves gradually to the bottom 28 of the groove `i'hc'iughthe interior i215 of the acoustical b'ase El is generally darker incolor, it is; however, not noticeable at the distance normallyencountered bet'tveen the eyes and the ceiling or Wall upon'vvhich ,itis installed; ln the course of applyiigthe (paint, there is a tendencyfor the excess amount to gradually ow down the slope and come to thesurface i2 at points 24 and 26. It should be noted that an acousticaliteni when in use as for instance` on a ceiling is inverted and theslotsor grooves I6 face the source of sound. Under those conditions, as Wellas when it is used Aon the Wall, the excess of the coatingcomposition"Willobviously under inuence of gravity flow down thevs'lope32 lto the surface I2. This 'flow 'not only decorates the visible partof the groove and therebyblending it into the fore'groiindto decreaseits visibility, but also prevents Vexcessive accumulation oi; thecoating composition Within the groove itself and thereby destroy orimpair Vits sound absorbing characteristics'. y Y u w At tinies'it maybe desirable to increase still further the s'd absorption and decreasethe eiect of the depth shadow of the groove. This can be readilyaccomplished by 'slotting the grooves ls, jdisgonauy from the surfacelf2, into the body I2b as shown in` Figure 5. Of'course, when this,particular rnodi'cation isvderectedvon the wan it isdesi'rabl that thegrooves point .downwardly to eliminate collection vof dirt andfacilitate future redecoration.

assises fgrsbveis In making acoustical tile according to the prin;yciples underlying this invention, the surface of a brous base such aslignocellulosic felted sheets isA simultaneously treated With heat andpressure under conditions mentioned previously. In practice it ispreferred to mold simultaneously the bevel I4 While heat and pressureare applied to This process provides a smooth, suitable lcoatingreceptive surface. In the preferred iiiodebfoperatiom the Whole seriesof 4 aneously cut by means of the desired nu'nit'ier of high speed saws.Each series of saws is mounted on a common shaft or spindle which inturn is driven by a high speed electric motor, The slotted or groovedacoustical tile is then'decoratediiithe customary manner, allowed to dryVand packaged for further disposition.

Though the above description describes in considerable detail theotstanding features and characteristics of the principles underlyingthis invention, it is obvious that many adaptations, extensions,modications and uses can readily be discerned by a person skilled inthis art, and it is not intended to be limited to the speciiicleinbodirnents described herein but only Aby the spirit of principles ofthis 'inveti'n'as indicated ini the attached claims.

1. In thev process of making a slotted acoustical tile, the steps ofdnsiying the surface o'f Va brous base by the application of heat andpressure to form a skin coat tl'1`re ')ri, penetr'atinsr the said vskincoat by'neans of a seriesfof parallel, cutting'r'neai'is to Vthe desireddepth. p

2. The proc'ssbf making` a slotted acoustical tile comprising the vstepsf applying a heated platen inaintained at a temperature of riot less vthan 350 F. to the surface of a fibrous ligncellulosic base board,simultaneously ei'i'ertirig* thereon a slight pressure to'cornp'resssaid surface, ymaintaining said 'heat and said pressure on said surfacefor a suiicient length of tine to coalesce the fibers in 'said Vsurfaceuntil d ensifled, coolingrtlie said den'sified 'surface and penetratingVto the desired depth the Ysaid surface by nas of a series of parallelcuttingrneans.

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UNiTEo STATE-s PATENTS

